Altered States of Consciousness
What is consciousness? What are the
different states of it? What does it mean
to alter it?
Salvador Dali, The Persistence of Memory, 1931
Who sleeps?
What is sleep?
A period of inactivity with raised thresholds to
arousal by external stimuli
The Electroencephalogram (EEG)
Measures electrical activity of groups of neurons
across the scalp.
An event-related potential (ERP) in the temporal lobe
caused by a simple auditory stimulus
Slow wave sleep (SWS)
Some characteristics of the sleep cycle
• The sleep/wake cycle is driven by a circadian rhythm
(24 hour rhythm).
• The sleep cycle (or bout) is driven by an ultradian
(less than 24 hour) rhythm. Your rest/activity activity
has a 90 minute ultradian rhythm.
• The sleep cycle has a period of 90-120 minutes. This
cycle may continue through wakefulness and may
explain ‘day dreaming’.
• The sleep cycle changes with age. As we get older,
we tend to have less REM sleep and more waking
bouts through the cycle.
Why sleep?
• Restoration theory
But … sleep deprivation does not interfere with physical
capabilities and does not initiate a stress response
• Preservation and protection theory
Animals that rely on vision tend to be diurnal (awake during
daylight) and those that rely more on other senses, and
are prey to visual animals, tend to be nocturnal (awake at
night)
• Energy conservation
Rembrandt ‘Sleeping Woman’ (1654)
Why dream?
• Real dreaming occurs during REM (rapid eye
movement) sleep. Stage 2 ‘dreaming’ is characterized
more as ‘sleep thought’.
• REM sleep is also called ‘paradoxical sleep’ because
the EEG pattern can look very much like the awake,
aware EEG pattern.
• Infants spend more time in REM sleep.
• If awakened during REM sleep alertness and
attentiveness are high. Being awakened during slow
wave sleep (Stage 4) drowsiness and confusion are
high.
• REM sleep deprivation causes irritability, problems
with procedural learning (consolidation) and REM
rebound.
The American Academy of Sleep Medicine (AASM)
offers the following tips on how to get a good
night’s sleep:
•Follow a consistent bedtime routine.
•Establish a relaxing setting at bedtime.
•Get a full night’s sleep every night.
•Avoid foods or drinks that contain caffeine, as well as any
medicine that has a stimulant, prior to bedtime.
•Do not bring your worries to bed with you.
•Do not go to bed hungry, but don’t eat a big meal before bedtime
either.
•Avoid any rigorous exercise within six hours of your bedtime.
•Make your bedroom quiet, dark and a little bit cool.
•Get up at the same time every morning.